1. Field of the Invention
The present invention relates to an external corner member, a constructing structure of external corner portion and a construction method of external corner portion using the same for a constructing external wall material on an external corner portion of a building without using any sealing material.
2. Description of the Related Art
When external wall board such as siding is attached on an external corner portion of a building, an external corner wall material is used to attach, and the external wall boards are attached to each side. Then, sealing material is poured into the right and left connections between the external corner wall material and the external wall boards for preventing water from infiltrating into the building through the connections. As the sealing material, a wet sealing material and a dry sealing material are known. The wet sealing material comprises a silicone or other resin, and it is poured and dried in a construction site. The dry sealing material is a previously-molded waterproof material, and it is engaged.
FIG. 8 shows an example of a conventional constructing structure of external corner portion in which the wet sealing material is used. As shown in FIG. 8, in the external covering of a building, waterproof papers G and furring strips H are installed sequentially to external side of a column F, and then an external corner wall material J and an external wall board K are attached to the column F by a fastening member I via the furring strips H. For pouring a sealing material M into the connections between the external corner wall material J and the external wall board K, a hat joiner L is installed to the interior side of the connection between the external corner wall material J and the external wall board K, so that a space (width, depth) for pouring the sealing material M is secured by the hat-shaped protruding portion of the hat joiner L. The sealing material M is poured into the space created between the surface of the protruding portion of the hat joiner L and the connection between the external corner wall material J and the external wall board K, so that side surfaces of the external corner wall material J are bonded to side surface of the external wall boards K and water does not infiltrate into the building. Similarly, another external corner wall material J and another external wall board K are attached on top of the constructed external corner wall material J and external wall board K, whereby the external wall is completed.
On the other hand, there is also a constructing structure of external corner portion for attaching an external wall material onto an external corner portion of a building without using a sealing material (see Japanese Patent Laid-Open No. 2000-345682).
FIG. 9 shows an example of constructing structure of external corner portion without using a sealing material. In the constructing structure of external corner portion of Japanese Patent Laid-Open No. 2000-345682, shiplap portions formed on both side edges of corner materials N configuring external corners are engaged to shiplap portions formed on sidings O, as shown in FIG. 9.
Moreover, there is another constructing structure of external corner portion without using a sealing material (see Japanese Patent Laid-Open No. 2003-328529).
As shown in FIG. 10, an external corner wall material P and external wall board Q are abutted to each other and a hat joiner S and packing E that are provided with waterproof materials R are used on the interior side of the vertical connection between the external corner wall material P and the external wall board Q.
However, the constructing structure of external corner portion with the sealing material has the following problems: (1) the durability and waterproof performance of the exposed sealing material becomes degraded due to age-related deterioration thereof, resulting in discoloration and degradation of the appearance; (2) the use of the sealing material inflates the construction cost; and (3) time and effort is involved in constructing the sealing material.
In the constructing structure of external corner portion disclosed in Japanese Patent Laid-Open No. 2000-345682, a sealing material is not poured into the connection between each corner material N and the sidings O, so that the problems (1) to (3) described above do not occur. But the following new problem arises: (4) shiplaps need to be processed in a construction site, which requires labor and increases the construction cost.
In the constructing structure of external corner portion disclosed in Japanese Patent Laid-Open No. 2003-328529, the problems (1) to (3) described above do not occur because a sealing material is not poured into the connection between the external corner wall material P and the external wall board Q, and the abovementioned problem (4) does not occur either because the external corner wall material P and the external wall board Q are abutted together. However, it is necessary to cut the external wall board Q at a construction site in order to abut, so that the following new problems arise: (5) a noticeable gap is formed easily in the abutting portion; and (6) it is necessary for apply a coating on the cut portion of the external wall board Q at the construction site, but the external corner wall material P is attached first in order to determine the position of the external wall board Q, so that workability turns worse because the cut portion of the external wall board Q cannot be applied with coating after attaching.